Growing Petunias

How to Plant, Grow, and Care for Petunias

Often grown as annuals, petunias are one of the most popular flowers because of their long flowering period. As with most annuals, they get leggy by midsummer, so you’ll want to prune the shoots back to about half their length. See how to plant and take care of your petunias to keep them blooming.

Pretty petunias are treated as annuals in most areas but also as tender perennials in Zones 9 to 11. The flowers come in many colors and patters, and bloom from spring until frost!

These colorful annuals can really add pop to a front lawn and often used as borders, containers, hanging baskets or even seasonal groundcover. Some even have a slight fragrance.

Height can vary from 6 inches to 18 inches. Spread can be from 18 inches to 4 feet.

Petunias are divided into different groups, mainly based on flower size:

Multiflora petunias are the most durable and prolific. They have smaller, but more abundant flowers and are ideal for summer bedding or in a mixed border (because they are more tolerant to wet weather).
Grandiflora petunias have very large flowers and are best grown in containers or hanging baskets (because they are more susceptible to rain damage). Theese large petunias often do not fare as well in the south because they’re prone to rot during humid, hot summers.
Floribundas: Floribundas are intermediate between the grandiflora and the multiflora groups. They are free-flowering like the multiflora varieties and produce medium-sized blooms.
Millifloras: Milliflora petunias are much smaller than any other petunias on the market. The flowers are only 1 to 1½ inches wide, but they are prolific and last all season!
Spreading or Trailing Petunias: These are low-growing but spread as much as 3 to 4 feet. They form a beautiful, colorful groundcover because the flowers form along the entire length of each stem. They can be used in window boxes or hanging baskets.

Planting

Petunias need full sun or they will become spindly. They don’t tend to flower in the shade.
They are quite versatile, growing in different types of soil, but it is important that the soil drains well and doesn’t stay wet.
You can grow petunias from seeds, but it is easier to grow them from transplants. If you are going to grow from seeds, start them indoors about 10 weeks before you want to set them outside. Petunia seeds are very small (dust-like!) and needs lots of light in order to germinate. Remember to water them. When the plants have three leaves, you can plant them outside.
It’s best to buy young plants from a nursery which often sells petunias in flats. Look for plants that are short and compact, not leggy and not yet blooming and they’ll settle in faster.
Plant after the last spring frost. (See your local frost dates) in a place that is sheltered from wind exposure. Keep well watered.
Space the plants about 1 foot apart.
If you’re planting petunias in containers, use a soil-less mix.

Care

Petunias are tolerant of heat so you don’t have to water them regularly. A thorough watering once a week should be sufficient (unless there are prolonged periods of drought in your area). Avoid watering shallowly as this encourages shallow roots.
Note: The spreading types of petunias and those in containers require more frequent watering.
Fertilize petunias monthly with a balanced fertilizer to support their rapid growth and heavy blooming. Double-flowered cultivars like a biweekly dose of fertilizer.

Getting Leggy in Midsummer

By midsummer, most petunias get leggy, producing blossoms at the tips of long, leafless stems. To keep petunias tidy and flowering, we prune the shoots back to about half their length. This will encourage more branching and flowers.
After pruning, fertilize and water the plants well to force out new growth and flowers. The plants may look raggedy at first but they’ll rebound with more color and blooms.
- Older garden petunia plants can be pruned prune hard (within a few inches of the base) to re-encourage vigor, especially in cooler climates, but keep the remaining leaves.
Also, remove faded, old, or dead blossoms to both improve blooms and attractiveness, especially for the larger-flowered petunias. Dead-heading prevents seed pods from competing for the plant’s food supplies. Clippings can be added to a compost pile to be recycled.

Pests/Diseases

Petunias have few serious insect or disease pests. Avoid wetting the foliage and flowers when watering to help prevent disease.

Aphids
Slugs

Recommended Varieties

Multifloras

‘Carpet Series’ is very popular. They are compact, early blooming with 1½-to 2-inch blooms that come in a wide variety of colors, and ideal for ground cover.
‘Primetime’ series stay compact and uniform, covered with 2¼-inch flowers.
‘Heavenly Lavender’ is an early, compact, double, deep lavender blue with 3-inch blooms on 12-to 14-inch plants

Grandifloras

‘Sugar Daddy’ (Petunia Daddy Series), which sports purple flowers with dark veins.
‘Rose Star’ (Petunia Ultra Series), whose flowers look striped because of its rose-pink flowers with a white center.

Floribundas

‘Celebrity’ series petunias are compact and rain-tolerant. The flowers reach 2½ to 3 inches across.
‘Madness’ series petunias have big, 3-inch flowers in many veined and solid colors. They are compact and bloom until frost. They bounce back well after rain.
‘Double Madness’ petunias are compact and floriferous with big, 3-inch flowers all through the summer. Like their single counterparts, ‘Double Madness’ petunias bounce back within hours of a rainstorm.

Millifloras

‘Fantasy’ forms neat, compact’Fantasy Pink Morn’, a milliflora type petunia.

Trailing Petunias

‘Purple Wave’ was the first cultivar in the class of spreading petunias. It produces large blooms of deep rose-purple. It is tolerant of summer heat, drought and rain damage. ‘Purple Wave’ remains under 4 inches tall.
‘Wave’ series petunias are available in a multitude of colors. Most are not quite as ground-hugging as the original. They are weather-tolerant, disease resistant and heavy-blooming.

What do you want to read next?

Spring-Flowering Bulbs to Plant in...

Easiest Roses to Grow for Beginners

Marigolds

When to Plant Flowers

The Best Fall Flowers for Your...

Caring for Perennial Flowers

Morning Glories

Tulips

10 Pretty Pansy Varieties

Potpourri: from the best annuals...

Growing Japanese Iris

Invasion of the Garden Catalogs--...

Reader Comments

Hi, Is it possible to grow up

Hi, Is it possible to grow up this in 32 Celsius? Please help me asap! Thanks in advance :)

Petunias are heat tolerant,

Petunias are heat tolerant, as long as they get a good, deep drink of water now and then. Encourage the roots to grow deep in well draining soil and 32 C shouldn't be a problem at all. In the states, they commonly grow in places that get above 37 C.

Nice.....best

Nice.....best ...information......!!

I bought some "wave" petunias

I bought some "wave" petunias a couple of weeks ago, and have been keeping them under my grow light until the danger of frost is gone. I notice , however, they have not grown,,they are still small,,have several blooms, but are not growing otherwise,,I wonder if you could tell me what to do to get these petunias to grow? I bought 6 of them so I hope they grow soon.

Hi, Linda, While outside

Hi, Linda,
While outside these plants need about 8 hours of sunlight, indoors, under a grow light, they require more: 16 to 18 hours daily at a height of 4 to 6 inches.
Best wishes—

Hi - My petunias were

Hi - My petunias were flowering beautifully, but suddenly, a blossom will start, then shrivel and die before opening. What am I doing wrong?

Usually petunias shrivel

Usually petunias shrivel because they are too wet. If you just bought the plants, they may already have root rot. You can gentle remove the root ball take a look. Petunias thrive on neglect and do not like wet feet.

does the seeds have to be

does the seeds have to be dryed before planting or can you plant them right after the flowers die?

Our sources suggest that it's

Our sources suggest that it's best to dry them first, Betty. Good luck—

We have bugs that look like

We have bugs that look like large Ticks eating only the white Petunias (also white Roses)? We are in the Central Valley in California. Can you tell me, are these Ticks or something else? They eat the entire white flowers.

It probably isn't a tick.

It probably isn't a tick. We're guessing some type of beetle. Google "jumping flea beetle" and "Japanese Beetle." It may be the latter as the Japanese Beetle loves roses. You can manage the flea beetle with organic insecticides. The Japanese beetle has to be caught early before they emerge and then handpicked and dropped in soapy water; they are difficult to manage once the plant is infested. Healthy plants that are growing in a clean, healthy soil appear to be less attractive to them.

Those are June Bugs! I used

Those are June Bugs! I used to live in the Central Valley too and they would eat my Mexican Primroses! They are a pain.

I am a retiree and live in

I am a retiree and live in Lahore Pakistan.I have a small garden at home and spend most of my time in growing various flowers specially annuals. This year I have full bloom of Petunias, looking beautiful. Most of the time I bought Seedlings from my local nursery but this year I managed to collect seeds from my own Petunias. All I want to know is when can I sow these seeds and a proper procedure to follow? Please keep in mind I am a beginner in gardening. Thanks.

Welcome, Aslam! A true

Welcome, Aslam!
A true beginner would go buy more seedlings; you are an advanced beginner!
Collect and dry the seeds. Spread them widely on a container of damp potting soil (very light material) or sphaghum moss. Mist water on them in a fine spray, then press them gently into the medium. Cover the container with clear plastic and put it in a warm (70 to 85°F), bright (not direct sunlight) place for 7 to 10 days, or until the seeds sprout. Remove the covering and place the container in a slightly cooler, still bright place. Ideally, if you have it, the best place is 4 to 6 inches below a florescent light, with the light on for 16 to 18 hours per day. When the plants develop true leaves, transplant them into seedling trays and fertilize every two weeks with a dliuted mixture. Harden them off by putting them outside on warm, sunny days.
We hope this helps. Let us know how you do!

Many thanks for your

Many thanks for your advise.Today I have officially planted the seeds in a plastic container, completely following your instructions,and have placed the container inside in a bright place after covering it with clear plastic. Now the question is how should I water it. A friend of mine told me to water it a little on every second day. Please advise before I mess it up.
Thanks in advance.

I'm going to be re-planting

I'm going to be re-planting the bed with new petunias, but wanted to check whether the dead-looking sticks (all that remains above ground from last summer), will come back to life and flower again this year... I know they are meant to be annuals so is this what they normally look like after their one season. Can I safely remove them and plant anew?

The petunias have died. Pull

The petunias have died. Pull them out and prepare your beds. Amend the soil by digging in compost a 1- to 2-inch layer of compost. Plant them outdoors once the weather and soil have warmed up, about the time you plant impatiens or peppers.

I am teaching high school

I am teaching high school botany and for a class project, we are using varying environments to grow petunias to see the effect. In order to preserve the experiment, I need a controlled environment. I have everything the same, UV light, temperature, etc, but I cannot find an exact measurement for water. All the sites say to touch the soil to see if its dry. I need something a little more exact to preserve our controlled environment. Do you have a suggested amount or frequency we can use?

one simple solution can be 1.

one simple solution can be
1. weigh a few spoonfuls of the soil as it is, let it be w1
2. heat the soil, an oven can do the job, to lose the moisture.
3. weigh the soil again, let it be w2

difference in the two weights, w1-w2, will be the weight of water per w2 weight of soil,

it is difficult to lose all the water from the soil and some may still remain attached to the soil even after
lots of heating. But it is likely to be very little for most of the soils which are fit for cultivation and one can ignore that.

one can go for very refined measurements also,

with best regards

Rajesh

I live in Southern Australia

I live in Southern Australia in a temperate climate. I planted petunia seedlings in late summer (that's mid February here). Do you think they will keep flowering into mid fall (April) when I want a nice display?

I have just bought new pink

I have just bought new pink petunia with white lines on it, after few blooms the color of flowers have changed to purple and white. My purple petunia do not touch pink ones.
I live in India, with max temp currently 27 C and min around 11 C

Fresh leaves of some of my

Fresh leaves of some of my potted petunias are turning out to be yellowish and the plant does not grow after that. Even the flowers in these yellowish parts are very small and look sickly. The plant just stays the same, no growth, nothing, after this yellowness happens.
The drainage is good, they get about 6-8 hours of sunlight, other nearby petunias, potted and cared for in the same way are doing well. Somebody has suggested putting some vinegar to make the soil acidic. Please help,
I have noticed this problem in the last few years only in Delhi, India. Now i see the same in other people's
petunias also.

Petunias are heavy feeders

Petunias are heavy feeders and grow best with a soil pH between 5.5 and 5.8. With a higher soil pH, petunias begin to suffer from iron deficiency. Try fertilizing with a fertilizer rich in iron.

thanks, will try rajesh

thanks, will try

rajesh

Our petunia looks like it's

Our petunia looks like it's wilting and it does look a bit fresher after it's watered, but doesn't improve much. I'm not sure what's going wrong.

Is you petunia outdoors? The

Is you petunia outdoors? The plant doesn't get as much sunlight in the winter months so if possible move it to a spot where it gets maximum sun. Give the petunia some fertilizer and remove all spent blossoms.

I live in Zimbabwe and want

I live in Zimbabwe and want to take cuttings off my hybrid petunias. Can you tell me what photoperiod can help? Our natural day-length is 10-14 hours and we get very hot and sunny most of the year, aye, Ian

Aye, Ian! Our sources suggest

Aye, Ian!
Our sources suggest that petunia are long-day plant that flower under any photoperiod. Short periods delay flowering and tends to result in "stretched" plants. See comments (answers above) for growing under florescent lights. Consider, too, night temps of 60°F to 63°F and daytime temps of 70°F to 75°F. Good luck with this—and thanks for asking from so far!

Can I plant petunias in the

Can I plant petunias in the same soil as year before and do petunias have an influence on other plants in the same pot or floor bed?

It's fine to plant petunias

It's fine to plant petunias in the same soil next year. Just add some well-rotted manure or compost before planting.
Petunias are great in the vegetable garden. They repel aphids, asparagus beetles, leafhoppers and tomato worms. Some plants that thrive with petunias as companions are basil, beans, tomatoes, corn and peppers. Roses and petunias also grow well together.